Question: Suppose the area of a circle is ${36\pi}$. What is its circumference?
Explanation: ${K = 36\pi}$ ${c = 12\pi}$ First, find the radius: $K = \pi r^2$ , so $r = \sqrt{K / \pi} = \sqrt{{36\pi} / \pi} = {6}$ Now find the circumference: $c = 2\pi r = 2\pi \cdot {6} = {12\pi}$.